What a night this is! Not looked at pPrune for months, then six posts in a row. I'm sure I'll regret it in the morning.
Both CDFA and constant angle descent avoid Step Down Fixes (resulting in more stable approach) BUT CDFA treats MDA as DA rather than proceeding to MAPt.
So, using CDFA, you fly a stable descent to MDA, then land or go around. The constant angle descent gives you a stable approach to MDA, (which may not coincide with MAPt) but then a level sector to MAPt. It suits helicopters, who are still allowed to do it.